Genta Ueno Nagatomo Nakamura Tomoyuki Higuchi Separation of Photoelectrons via Multivariate Maxwellian Mixture Model. 470-475 2001 conf/dis/2001 Discovery Science http://link.springer.de/link/service/series/0558/bibs/2226/22260470.htm db/conf/dis/dis2001.html#UenoNH01